-18x2 -5x +2 = 0
ax2 bx c = 0
a = -18
b = -5
c = 2
Δ = b2-4ac
Δ = -5² - (4 * -18 * 2)
Δ = 25 - (4*-36)
Δ = 25 - (-144)
Δ = 169 Δ > 0
-18x2-5x+2=0
x = -b ∓ √Δ 2a
x' = 5 - √169 2*-18 = 5 - 13.0 -36 = -8.0 -36 = 0.222222222222
x" = 5 + √169 2*-18 = 5 + 13.0 -36 = 18.0 -36 = -0.5
x' = 72.0
x" = -162.0
S = {x ∈ R / x' = 72.0, x" = -162.0 }